OvmfPkg/LocalApicTimerDxe/LocalApicTimerDxe.c

   1 /** @file
   2   Timer Architectural Protocol as defined in the DXE CIS
   3
   4 Copyright (c) 2005 - 2018, Intel Corporation. All rights reserved.<BR>
   5 Copyright (c) 2019, Citrix Systems, Inc.
   6
   7 SPDX-License-Identifier: BSD-2-Clause-Patent
   8
   9 **/
  10
  11 #include "LocalApicTimerDxe.h"
  12
  13 //
  14 // The handle onto which the Timer Architectural Protocol will be installed
  15 //
  16 EFI_HANDLE  mTimerHandle = NULL;
  17
  18 //
  19 // The Timer Architectural Protocol that this driver produces
  20 //
  21 EFI_TIMER_ARCH_PROTOCOL  mTimer = {
  22   TimerDriverRegisterHandler,
  23   TimerDriverSetTimerPeriod,
  24   TimerDriverGetTimerPeriod,
  25   TimerDriverGenerateSoftInterrupt
  26 };
  27
  28 //
  29 // Pointer to the CPU Architectural Protocol instance
  30 //
  31 EFI_CPU_ARCH_PROTOCOL  *mCpu;
  32
  33 //
  34 // The notification function to call on every timer interrupt.
  35 // A bug in the compiler prevents us from initializing this here.
  36 //
  37 EFI_TIMER_NOTIFY  mTimerNotifyFunction;
  38
  39 //
  40 // The current period of the timer interrupt
  41 //
  42 volatile UINT64  mTimerPeriod = 0;
  43
  44 //
  45 // Worker Functions
  46 //
  47
  48 /**
  49   Interrupt Handler.
  50
  51   @param InterruptType    The type of interrupt that occurred
  52   @param SystemContext    A pointer to the system context when the interrupt occurred
  53 **/
  54 VOID
  55 EFIAPI
  56 TimerInterruptHandler (
  57   IN EFI_EXCEPTION_TYPE  InterruptType,
  58   IN EFI_SYSTEM_CONTEXT  SystemContext
  59   )
  60 {
  61   EFI_TPL  OriginalTPL;
  62
  63   OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
  64
  65   if (mTimerNotifyFunction != NULL) {
  66     //
  67     // @bug : This does not handle missed timer interrupts
  68     //
  69     mTimerNotifyFunction (mTimerPeriod);
  70   }
  71
  72   gBS->RestoreTPL (OriginalTPL);
  73
  74   DisableInterrupts ();
  75   SendApicEoi ();
  76 }
  77
  78 /**
  79
  80   This function registers the handler NotifyFunction so it is called every time
  81   the timer interrupt fires.  It also passes the amount of time since the last
  82   handler call to the NotifyFunction.  If NotifyFunction is NULL, then the
  83   handler is unregistered.  If the handler is registered, then EFI_SUCCESS is
  84   returned.  If the CPU does not support registering a timer interrupt handler,
  85   then EFI_UNSUPPORTED is returned.  If an attempt is made to register a handler
  86   when a handler is already registered, then EFI_ALREADY_STARTED is returned.
  87   If an attempt is made to unregister a handler when a handler is not registered,
  88   then EFI_INVALID_PARAMETER is returned.  If an error occurs attempting to
  89   register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR
  90   is returned.
  91
  92
  93   @param This             The EFI_TIMER_ARCH_PROTOCOL instance.
  94   @param NotifyFunction   The function to call when a timer interrupt fires.  This
  95                           function executes at TPL_HIGH_LEVEL.  The DXE Core will
  96                           register a handler for the timer interrupt, so it can know
  97                           how much time has passed.  This information is used to
  98                           signal timer based events.  NULL will unregister the handler.
  99
 100   @retval        EFI_SUCCESS            The timer handler was registered.
 101   @retval        EFI_UNSUPPORTED        The platform does not support timer interrupts.
 102   @retval        EFI_ALREADY_STARTED    NotifyFunction is not NULL, and a handler is already
 103                                         registered.
 104   @retval        EFI_INVALID_PARAMETER  NotifyFunction is NULL, and a handler was not
 105                                         previously registered.
 106   @retval        EFI_DEVICE_ERROR       The timer handler could not be registered.
 107
 108 **/
 109 EFI_STATUS
 110 EFIAPI
 111 TimerDriverRegisterHandler (
 112   IN EFI_TIMER_ARCH_PROTOCOL  *This,
 113   IN EFI_TIMER_NOTIFY         NotifyFunction
 114   )
 115 {
 116   //
 117   // Check for invalid parameters
 118   //
 119   if ((NotifyFunction == NULL) && (mTimerNotifyFunction == NULL)) {
 120     return EFI_INVALID_PARAMETER;
 121   }
 122
 123   if ((NotifyFunction != NULL) && (mTimerNotifyFunction != NULL)) {
 124     return EFI_ALREADY_STARTED;
 125   }
 126
 127   mTimerNotifyFunction = NotifyFunction;
 128
 129   return EFI_SUCCESS;
 130 }
 131
 132 /**
 133
 134   This function adjusts the period of timer interrupts to the value specified
 135   by TimerPeriod.  If the timer period is updated, then the selected timer
 136   period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned.  If
 137   the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
 138   If an error occurs while attempting to update the timer period, then the
 139   timer hardware will be put back in its state prior to this call, and
 140   EFI_DEVICE_ERROR is returned.  If TimerPeriod is 0, then the timer interrupt
 141   is disabled.  This is not the same as disabling the CPU's interrupts.
 142   Instead, it must either turn off the timer hardware, or it must adjust the
 143   interrupt controller so that a CPU interrupt is not generated when the timer
 144   interrupt fires.
 145
 146
 147   @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
 148   @param TimerPeriod     The rate to program the timer interrupt in 100 nS units.  If
 149                          the timer hardware is not programmable, then EFI_UNSUPPORTED is
 150                          returned.  If the timer is programmable, then the timer period
 151                          will be rounded up to the nearest timer period that is supported
 152                          by the timer hardware.  If TimerPeriod is set to 0, then the
 153                          timer interrupts will be disabled.
 154
 155   @retval        EFI_SUCCESS       The timer period was changed.
 156   @retval        EFI_UNSUPPORTED   The platform cannot change the period of the timer interrupt.
 157   @retval        EFI_DEVICE_ERROR  The timer period could not be changed due to a device error.
 158
 159 **/
 160 EFI_STATUS
 161 EFIAPI
 162 TimerDriverSetTimerPeriod (
 163   IN EFI_TIMER_ARCH_PROTOCOL  *This,
 164   IN UINT64                   TimerPeriod
 165   )
 166 {
 167   UINT64  TimerCount;
 168   UINT32  TimerFrequency;
 169   UINT32  DivideValue = 1;
 170
 171   if (TimerPeriod == 0) {
 172     //
 173     // Disable timer interrupt for a TimerPeriod of 0
 174     //
 175     DisableApicTimerInterrupt ();
 176   } else {
 177     TimerFrequency = PcdGet32 (PcdFSBClock) / DivideValue;
 178
 179     //
 180     // Convert TimerPeriod into local APIC counts
 181     //
 182     // TimerPeriod is in 100ns
 183     // TimerPeriod/10000000 will be in seconds.
 184     TimerCount = DivU64x32 (
 185                    MultU64x32 (TimerPeriod, TimerFrequency),
 186                    10000000
 187                    );
 188
 189     // Check for overflow
 190     if (TimerCount > MAX_UINT32) {
 191       TimerCount = MAX_UINT32;
 192       /* TimerPeriod = (MAX_UINT32 / TimerFrequency) * 10000000; */
 193       TimerPeriod = 429496730;
 194     }
 195
 196     //
 197     // Program the timer with the new count value
 198     //
 199     InitializeApicTimer (DivideValue, (UINT32)TimerCount, TRUE, LOCAL_APIC_TIMER_VECTOR);
 200
 201     //
 202     // Enable timer interrupt
 203     //
 204     EnableApicTimerInterrupt ();
 205   }
 206
 207   //
 208   // Save the new timer period
 209   //
 210   mTimerPeriod = TimerPeriod;
 211
 212   return EFI_SUCCESS;
 213 }
 214
 215 /**
 216
 217   This function retrieves the period of timer interrupts in 100 ns units,
 218   returns that value in TimerPeriod, and returns EFI_SUCCESS.  If TimerPeriod
 219   is NULL, then EFI_INVALID_PARAMETER is returned.  If a TimerPeriod of 0 is
 220   returned, then the timer is currently disabled.
 221
 222
 223   @param This            The EFI_TIMER_ARCH_PROTOCOL instance.
 224   @param TimerPeriod     A pointer to the timer period to retrieve in 100 ns units.  If
 225                          0 is returned, then the timer is currently disabled.
 226
 227   @retval EFI_SUCCESS            The timer period was returned in TimerPeriod.
 228   @retval EFI_INVALID_PARAMETER  TimerPeriod is NULL.
 229
 230 **/
 231 EFI_STATUS
 232 EFIAPI
 233 TimerDriverGetTimerPeriod (
 234   IN EFI_TIMER_ARCH_PROTOCOL  *This,
 235   OUT UINT64                  *TimerPeriod
 236   )
 237 {
 238   if (TimerPeriod == NULL) {
 239     return EFI_INVALID_PARAMETER;
 240   }
 241
 242   *TimerPeriod = mTimerPeriod;
 243
 244   return EFI_SUCCESS;
 245 }
 246
 247 /**
 248
 249   This function generates a soft timer interrupt. If the platform does not support soft
 250   timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.
 251   If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()
 252   service, then a soft timer interrupt will be generated. If the timer interrupt is
 253   enabled when this service is called, then the registered handler will be invoked. The
 254   registered handler should not be able to distinguish a hardware-generated timer
 255   interrupt from a software-generated timer interrupt.
 256
 257
 258   @param This              The EFI_TIMER_ARCH_PROTOCOL instance.
 259
 260   @retval EFI_SUCCESS       The soft timer interrupt was generated.
 261   @retval EFI_UNSUPPORTED   The platform does not support the generation of soft timer interrupts.
 262
 263 **/
 264 EFI_STATUS
 265 EFIAPI
 266 TimerDriverGenerateSoftInterrupt (
 267   IN EFI_TIMER_ARCH_PROTOCOL  *This
 268   )
 269 {
 270   EFI_TPL  OriginalTPL;
 271
 272   if (GetApicTimerInterruptState ()) {
 273     //
 274     // Invoke the registered handler
 275     //
 276     OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
 277
 278     if (mTimerNotifyFunction != NULL) {
 279       //
 280       // @bug : This does not handle missed timer interrupts
 281       //
 282       mTimerNotifyFunction (mTimerPeriod);
 283     }
 284
 285     gBS->RestoreTPL (OriginalTPL);
 286   } else {
 287     return EFI_UNSUPPORTED;
 288   }
 289
 290   return EFI_SUCCESS;
 291 }
 292
 293 /**
 294   Initialize the Timer Architectural Protocol driver
 295
 296   @param ImageHandle     ImageHandle of the loaded driver
 297   @param SystemTable     Pointer to the System Table
 298
 299   @retval EFI_SUCCESS            Timer Architectural Protocol created
 300   @retval EFI_OUT_OF_RESOURCES   Not enough resources available to initialize driver.
 301   @retval EFI_DEVICE_ERROR       A device error occurred attempting to initialize the driver.
 302
 303 **/
 304 EFI_STATUS
 305 EFIAPI
 306 TimerDriverInitialize (
 307   IN EFI_HANDLE        ImageHandle,
 308   IN EFI_SYSTEM_TABLE  *SystemTable
 309   )
 310 {
 311   EFI_STATUS  Status;
 312
 313   //
 314   // Initialize the pointer to our notify function.
 315   //
 316   mTimerNotifyFunction = NULL;
 317
 318   //
 319   // Make sure the Timer Architectural Protocol is not already installed in the system
 320   //
 321   ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);
 322
 323   //
 324   // Find the CPU architectural protocol.
 325   //
 326   Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **)&mCpu);
 327   ASSERT_EFI_ERROR (Status);
 328
 329   //
 330   // Force the timer to be disabled
 331   //
 332   Status = TimerDriverSetTimerPeriod (&mTimer, 0);
 333   ASSERT_EFI_ERROR (Status);
 334
 335   //
 336   // Install interrupt handler for Local APIC Timer
 337   //
 338   Status = mCpu->RegisterInterruptHandler (
 339                    mCpu,
 340                    LOCAL_APIC_TIMER_VECTOR,
 341                    TimerInterruptHandler
 342                    );
 343   ASSERT_EFI_ERROR (Status);
 344
 345   //
 346   // Force the timer to be enabled at its default period
 347   //
 348   Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);
 349   ASSERT_EFI_ERROR (Status);
 350
 351   //
 352   // Install the Timer Architectural Protocol onto a new handle
 353   //
 354   Status = gBS->InstallMultipleProtocolInterfaces (
 355                   &mTimerHandle,
 356                   &gEfiTimerArchProtocolGuid,
 357                   &mTimer,
 358                   NULL
 359                   );
 360   ASSERT_EFI_ERROR (Status);
 361
 362   return Status;
 363 }